A McDonald's spokesperson told the AP that select locations in Alabama, Georgia, Louisiana, Mississippi, and South Carolina will begin serving the McGriddle all day next week.

Adding the much-loved McGriddle to the all-day-breakfast menu would help fix customers' No. 1 issue with McDonald's all-day breakfast: It doesn't include many of their breakfast favorites.

Currently, most locations offer a limited breakfast menu all day, serving either McMuffins or biscuit breakfast sandwiches based on regional preferences. McGriddles and bagels are not on the national all-day menu.

"Many customers are frustrated about the limited menu," one franchisee wrote in response to a recent survey by Nomura analyst Mark Kalinowski. "I am in a McMuffin market that was almost evenly split, and I have customers furious that they cannot get biscuits. They feel that it is a sham or false advertising."

Another franchisee complained about "explaining to irate customers why the breakfast menu is so limited."

McDonald's hasn't previously included the McGriddle and other breakfast items on the all-day-breakfast menu due to potential kitchen complications. According to some franchisees and employees, all-day breakfast has already created more work and resulted in overcrowding in kitchens, due to new equipment.

However, when it comes to sales, all-day breakfast is paying off big for the fast-food chain. McDonald's same-store sales in the US grew 5.7% in the most recent quarter, thanks in large part to the success of all-day breakfast.